From design to biological evaluation: AT11-liposomes boost imiquimod potential in tongue cancer cells

Persistent Human Papillomavirus (HPV) infections can progress through a multistep carcinogenesis process, ultimately leading to invasive cancers. Imiquimod (IQ), a topical agent with antiviral and antitumoral properties, has shown promising outcomes in HPV-related pre-malignant lesions and even oral cancer case reports; however, its clinical application remains limited by poor solubility and low tissue selectivity. To overcome these challenges, nanoparticle-based systems such as liposomes, widely recognized for their safety and effectiveness in drug delivery, represent a promising strategy to enhance IQ therapy for oral cancers. Functionalization with targeting ligands may further enhance their selectivity. In this context, the nucleolin-binding aptamer AT11, which folds into a G-quadruplex structure, represents a valuable targeting moiety to promote selective drug accumulation in cancer cells.

Empty or IQ-loaded liposomes were prepared by the ethanol injection method and subsequently functionalized with AT11-TEG-Cholesteryl, yielding nanoparticles with hydrodynamic diameters of ~120-140 nm, and with %EE of ~83%. Their biological performance was assessed in squamous cell carcinoma of the tongue (UPCI-SCC-154) and non-malignant esophageal epithelial (Het1A) cells. Regarding their biological potential, AT11 IQ-associated liposomes allowed a selective delivery of IQ towards a tongue cancer cell line relative to the non-malignant cell line. Specifically, they induced a selective reduction of cell viability, proliferation and increased cell death. Additionally, they decreased the migration and invasion capacities of the cancer cells.

Overall, these findings highlight AT11-functionalized liposomes as a promising nanocarrier to improve the IQ selectivity and anticancer potential.

Acknowledgements:

Carla Cruz acknowledges the project Oralcare (ref. 12111309) winner of the UBI-CGD Innovation Award 2024, funded under the UBI-CGD 2023 Multiannual Patronage Agreement established between Caixa Geral de Depósitos and UBI, and also the “Projetos de Ignição e Provas de Conceito INOVC+”